The present invention generally relates to a storage controller and a storage control method, and in particular relates to a storage controller connected to a host system and which stores data to be sent to and received from the host system in an HDD (Hard Disk Drive) as a storage device according to a RAID (Redundant Arrays of Inexpensive Disks) system, and to the storage control method thereof.
As this type of storage controller, for instance, known is a type comprising a drive with a rotating storage device for storing data, and a storage controller interposed between the drive and a host system and which controls the sending and receiving of data between the drive and the host system (refer to Japanese Patent Laid-Open Publication No. H11-191037; “Patent Document 1”).
Patent Document 1 describes recovering, when a disk drive fails and becomes inoperative, all data of the failed drive from the remaining drives of the ECC group (RAID group) and copying such data to a spare disk drive (correction copy).
Further, a storage control system comprising a spare disk drive has been proposed for recovering, when one of the disk drives configuring RAID fails, data from the other disk drives configuring RAID, and recovering the status from the degenerate status of RAID to the normal access status where all disk drives configuring RAID are operable (refer to Japanese Patent Laid-Open Publication No. 2002-297322; “Patent Document 2”).
Moreover, a storage control system has been proposed comprising a disk array controller, a disk drive connected to a disk array controller via a drive interface and for storing a plurality of data aligned in an array, and a data backup device for backing up data stored in the disk drive, wherein a plurality of disk drives are used as spare disk drives, and the remaining disk drives are used as data/parity disk drives for storing data and the like, and a spare disk drive is used as a data/parity disk drive in substitute for the failed data/parity disk drive (refer to Japanese Patent Laid-Open Publication No. H6-139027).
In addition, as a storage controller, known is a rack mount-type disk array apparatus. With this rack mount-type disk array apparatus, a plurality of hard disk units and an interface unit are provided replaceably inside a rack mounted on the chassis. When replacing the hard disk unit, the user removes the hard disk unit to be replaced from the front face of the chassis, and mounts a new hard disk unit.
Meanwhile, in order to facilitate the maintenance associated with a failure of a disk drive, a method is being attempted of making the failed disk drive subject to a failure unexchangeable, and, when a disk drive configuring RAID fails, mounting a repair disk drive in a spare disk drive, and using the repair disk drive in substitute for the failed disk drive. Here, when one of the disk drives configuring RAID fails, data can be reproduced from the other disk drives configuring RAID and stored in the spare disk drive, the spare disk drive can be configured as a data disk drive, and the repair disk drive mounted in the spare disk drive can be configured as a spare disk drive (refer to Patent Document 2). Incidentally, a storage controller that sends and receives information to and from a host computer has also been proposed (refer to Japanese Patent Laid-Open Publication No. H7-146760).